The NSW government must explain to taxpayers what will happen to Sydney's Cross City Tunnel if no private buyer is found for the project, the opposition says.

NSW 'must come clean over tunnel'

The NSW government must explain to taxpayers what will happen to Sydney's Cross City Tunnel if no private buyer is found for the cash-strapped project, the opposition says.

Receivers KordaMentha have been appointed to administer the tunnel by a syndicate of 16 domestic and international banks, including Westpac and Deutsche Bank, who are owed about $560 million.

NSW Roads Minister Eric Roozendaal said he would not comment on any potential buyers of the tunnel should it be put up for sale, but said the government was not interested in purchasing it.

However, if no private buyer is found, and the tunnel sinks into further trouble, under the contract the Roads and Transport Authority (RTA) has the power to step in and keep the road open.

Opposition roads spokesman Andrew Stoner said the government had to come clean on what would happen if no private buyer was found for the tunnel.

"(NSW Premier) Morris Iemma and Eric Roozendaal must explain ... how much money taxpayers will be forced to shell out to fix Labor's mistakes," Mr Stoner said.

He echoed comments by former NSW auditor-general Tony Harris, who said the tunnel's failure had put the private sector on notice about the dangers of entering into any contract with the NSW government.

Mr Stoner said NSW now had a dreadful reputation among the private sector in relation to private-public partnerships.

"NSW now has a dreadful reputation amongst would-be infrastructure investors over their handling of the Cross City Tunnel fiasco, and this is likely to affect the level of interest in purchasing the tunnel," he said.